1. Field of the Invention
The present invention relates to a chemical amplification type positive resist composition.
2. Prior Art
For fine processing of semiconductors, a lithography process using a resist composition is usually adopted, and in lithography, it is theoretically possible to increase resolution higher when exposure wavelength is shorter as represented by the Raleigh diffraction limitation formula. As the exposure light source for lithography used for production of semiconductors, there are g ray having a wavelength of 436 nm, i ray having a wavelength of 365 nm, KrF excimer laser having a wavelength of 248 nm and ArF excimer laser having a wavelength of 193 nm, developed in this order, the wavelength becoming shorter year by year. Further, as the exposure light source of the next generation, F2 excimer laser having a wavelength of 157 nm is promising. For exposure to KrF excimer laser and ArF excimer laser, what is called chemical amplification type resists utilizing the catalytic action of an acid generated by exposure are often used due to excellent sensitivity. Further, also for exposure to F2 excimer laser, there is a high possibility of use of chemical amplification type resists due to a excellent sensitivity.
However, resins used in resists for KrF excimer laser exposure and ArF excimer laser exposure do not show sufficient transmittance for lights of wavelengths of 170 nm or less, for example, F2 excimer laser having a wavelength of 157 nm. When transmittance is lower) various properties such as profile, contrast, sensitivity and the like are badly influenced.
An object of the present invention is to provide a resist composition excellent in transmittance for light of a wavelength of 170 nm or less and suitable particularly for F2 excimer laser lithography.
The present inventors have found that a resist composition improved in transmittance at a F2 excimer laser wavelength of 157 nm and excellent in balance of abilities such as sensitivity, resolution and the like can be produced by using a resin containing a structural unit having a specific skeleton.